from random import randint

results = []

for i in range(1000000):
    numbers = range(100) # list with 100 elements [0, 1, ... 99]
    look_for_this_number = randint(0, len(numbers)-1)
    result = 0
    for j in range(5): # pick 5 random numbers from the list
        ri = randint(0, len(numbers)-1)
        number = numbers.pop(ri)
        if look_for_this_number == number: result = 1 # correct number picked!
    results.append(result)

print "p:", sum(results)/float(len(results))